The present invention relates to a power supply circuit, and for example, to a technique of using ambient radio signals as an alternating-current power supply and generating a direct-current power supply from the alternating-current power supply.
In recent years, a great deal of attention has been focused on efficient use of energy. One of the methods for efficiently using energy is an energy recovery technique. One example of the energy recovery techniques is disclosed in Japanese Unexamined Patent Application Publication No. 8-237063.
Japanese Unexamined Patent Application Publication No. 8-237063 discloses an output synthesis circuit including transformers formed of a plurality of unit transformers including primary windings to which outputs of high-frequency power amplifiers are added and secondary windings directly connected to each other, the secondary windings of the transformers being connected in parallel.